Fix KNetProducerRecord to conform to Apache Kafka expectation

[masesdevelopers]

Description

The PR changes the way the data are reported in case they are not set when a KNetProducerRecord is created. This will help to conform to Apache Kafka requirements of ProducerRecord.

Related Issue

Closed #223

Motivation and Context

How Has This Been Tested?

Locally tested

Screenshots (if appropriate):

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)

Checklist:

• My code follows the code style of this project.
• My change requires a change to the documentation.
• I have updated the documentation accordingly.
• I have read the CONTRIBUTING document.
• I have added tests to cover my changes.
• All new and existing tests passed.